1. Field of the Invention
The invention relates to a robot control method, a robot control device, and a robot control system, and in particular to a robot control method, robot control device, and a robot control system for controlling a robot having at least one redundant degree of freedom that is redundant with respect to task degrees of freedom.
2. Description of Related Art
A computed torque controller for a robot arm as disclosed in Japanese Patent Application Publication No. 4-98304 (JP 4-98304 A) is known. The controller described in JP 4-98304 A calculates the inertia force, Coriolis force, centripetal force, and gravity force in real time, by correcting a target angular acceleration, using a state feedback value derived from a deviation of an output value of an angle at each given sampling period from a target value of the angle, and a deviation of an angular velocity from its target value, according to a motion of the robot arm, and controls the motion of the robot arm by causing a joint driving actuator to generate torque equivalent to the above-indicated forces.
By calculating the above-indicated inertia force and others in real time and giving torque to a motor for rotating or driving the robot arm as described above, the controllability can be improved.
If the inertia force and others are calculated in real time, and equivalent torque is given to a motor for rotating or driving a robot arm, in a robot having a redundant degree or degrees of freedom which is/are redundant with respect to task degrees of freedom, excessively large torque may have to be generated, depending on the posture or orientation of the robot. In this case, the controllability may deteriorate.